1. Field of the Invention
The present invention relates to a certificate issuing system, a client terminal, a server device, a certificate acquisition method, and a certificate issuing method. For example, the present invention relates to a certificate issuing system that issues a client certificate to a client terminal, and the like.
2. Description of the Related Art
Hitherto, an authentication process using a digital certificate has been performed in order to increase safety in network communication. The digital certificate is issued by, for example, a certificate authority (CA).
As a certificate issuing system of the related art, there has been known a system in which a server device connected to a terminal through a network generates a public key pair (secret key and public key) and a client certificate of a client device (terminal) and writes the generated public key pair and client certificate in the terminal through a network (see Japanese Patent Unexamined Publication No. 2009-260508).
For example, in the system disclosed in Japanese Patent Unexamined Publication No. 2009-260508, the server device generates a secret key and signs a public key certificate for a public key of the client device (terminal) using the secret key of the server device to thereby create a certificate of the client device (client certificate). The system transmits the secret key of the client device which is encrypted by a password and the client certificate to the client device.
For example, Japanese Patent Unexamined Publication No. 9-305661 discloses a system that writes a certificate of a client device (terminal) (client certificate) during the manufacture of a terminal, as a certificate issuing system of the related art. In the system, a certificate management device generates a client certificate and a secret key during the manufacture of the terminal.
In the systems disclosed in Japanese Patent Unexamined Publication No. 2009-260508 and Japanese Patent Unexamined Publication No. 9-305661, it is difficult to reduce the risk of leakage of the secret key of the client terminal and to improve safety in issuing the client certificate.